Causes include increased stimulation threshold at electrode site (exit block), poor lead contact, new bundle branch block or programming problems.Undersensing occurs when the pacemaker fails to sense native cardiac activity.Note: Normal pacemaker function is discussed extensively in a seperate post. Diagnosis of pacemaker malfunction is challenging and often associated with non-specific clinical symptoms while ECG changes can be subtle or absent.Pacemaker malfunction can occur for a wide variety of reasons, ranging from equipment failure to changes in underlying native rhythm.↪ ECG Library Homepage Pacemaker Malfunction Overview
